1. Field of the Invention
The present invention relates to a liquid ejection head that performs recording operation by ejecting liquid, a method for evaluation of a liquid ejection head, and a liquid ejection apparatus having a liquid ejection head.
2. Description of the Related Art
A liquid ejection head typified by an ink-jet recording head can perform recording operation by ejecting liquid from ejection orifices. The ejection orifices are provided in an ejection orifice member provided on a liquid ejection head substrate having energy generating elements that generate energy used for ejecting liquid. The size of ejected liquid droplets heavily depends on the opening area of the ejection orifices. Therefore, if the opening area varies from head to head, the size of liquid droplets varies from head to head, and the recording quality is uneven.
A method for checking the opening area of ejection orifices without actually ejecting liquid droplets is disclosed in U.S. Pat. No. 6,830,309 and Japanese Patent Laid-Open No. 2007-098701. A liquid ejection head disclosed in U.S. Pat. No. 6,830,309 has, in addition to ejection orifices that eject liquid, a dummy ejection orifice and can estimate the opening area of the ejection orifices by counting pixels of an image of the dummy ejection orifice.
A diagram disclosed in Japanese Patent Laid-Open No. 2007-098701 is shown in FIG. 15. An ejection orifice member 20 having ejection orifices 21 and flow passages 22 is provided on a liquid ejection head substrate 14 having heat generating elements 11. An exposure mask used for forming the ejection orifices 21 of the ejection orifice member 20 has a plurality of slit-like masks having different widths near the ejection orifices 21. By performing exposure and development using such an exposure mask, the ejection orifices 21 and a plurality of slits 23 are formed in the ejection orifice member 20. By evaluating the number and/or the deformation amount of the slits formed in the ejection orifice member 20, the diameter of the ejection orifices 21 can be estimated.
However, in the case of the method disclosed in U.S. Pat. No. 6,830,309, it is necessary to capture an image of the liquid ejection head using a microscope and to binarize and count pixels in image processing, and it takes time to estimate the opening diameter. Therefore, this method is not adequate for mass production.
The method disclosed in Japanese Patent Laid-Open No. 2007-098701 is an indirect measurement method such that the shape of slits is checked in place of the opening shape of ejection orifices. It is open to question whether a factor that influences the opening shape of ejection orifices always also influences the shape of slits to the same degree.